1. Field of the Invention
The present invention is directed toward automobile manufacturing processes and, more particularly, toward a method and apparatus for pre-cleaning an automobile body prior to a painting process.
2. Description of Related Art
During the manufacture of automobiles, and before the automobile is painted, the body panels are welded, bolted, or otherwise installed on the automobile frame. Typically, all of the metal body panels, including the fenders, hood, trunk lid and doors, are secured to the frame. This structural assembly is referred to in the field and hereinafter as the "white body".
Before being painted, the white body must be cleaned to remove oil, grease, and residual metal that would result in a flaw in the finished paint surface. The residual metal, which is especially difficult to remove, include the by-products of welding, such as welding balls and metal particles. Accordingly, there has been much attention to the efficient and economical cleaning of the white body.
It is known in the art to clean the white body by means of a deluge cleaning system wherein the automobile is initially flooded with a cleaning solution, typically water, at least partially immersed in a cleaning bath containing the cleaning solution, and then flooded again with cleaning solution. One or more spray bars may also be used to spray cleaning solution onto the exterior surfaces of the white body, both before and after immersion in the cleaning solution bath, to rinse the white body.
The prior art inlet deluge cannon is disposed over the cleaning bath. Accordingly, initial flooding of the white body takes place at the entrance of the cleaning solution bath, typically at the upstream side, and is accomplished by means of a series of deluge nozzles. The deluge nozzles flood the white body interior, via one of more window openings, with cleaning solution. The flow of cleaning solution liberates metal particles, such as welding balls, from the white body interior. The used cleaning solution flows from the white body, together with entrained particles, and into the cleaning solution bath.
Subsequent immersion of the white body in the cleaning solution bath releases further metal particles into the cleaning solution bath. Moreover, the second flooding of the white body via second deluge nozzles essentially rinses any remaining particles from the white body into the cleaning solution bath.
The cleaning solution bath is defined by a container or tank holding a large volume of cleaning solution. The container has a bottom drain by means of which cleaning solution and particles exit the container and are delivered to a filtration and fluid distribution system. The prior art filtration and fluid distribution system takes cleaning solution and entrained particles from the cleaning solution bath, separates or filters the particles therefrom, and provides the filtered cleaning solution, pressurized by means of pumps, back to the deluge nozzles and/or spray bars of the deluge cleaning system.
As can be appreciated from the foregoing, due to the nature of the material being removed from the white bodies and subsequently removed from the cleaning solution bath, the deluge cleaning systems known in the art are under considerable operational stress and suffer from several significant drawbacks.
Although the particles deposited on the white bodies come in different densities, sizes, and shapes, they can generally be classified into a first group that sinks and a second group that floats. The group of particles that sink have a tendency to accumulate along the bottom surface of the tank, and forces the tank to be cleaned frequently. The group of particles that float have a tendency to accumulate at, or just under, the upper surface of the cleaning solution bath, and present a significant problem in the system. Namely, the floating particles have a tendency to be redeposited on the surface of subsequently submerged or immersed white bodies. The more white bodies that are processed, the more of a problem that these two groups of particles present.
As the filtration system becomes loaded with filtered particles, there is a tendency for the rate of cleaning solution flow through the deluge nozzles into the interior of the white body to drop. Accordingly, the fluid pressure and rate of flow at the deluge nozzles varies from high levels when the filters are clean to relatively low levels when the filters are clogged. Unfortunately, high pressure/flow may result in damage to the white body, typically to the weld sealer. Low pressure/flow may provide inadequate cleaning of the white body. Also, variations in the flow rate and pressure of the cleaning solution yields inconsistent results, which is undesirable.
Accordingly, there exists a need in the art for a method and device for eliminating or reducing the problems associated with metal particles in the cleaning solution bath. There also exists a need in the art for a device and method for supplying a relatively constant volume of cleaning solution to the deluge nozzles of the deluge cleaning system. Finally, there exists a need in the art for an improved system wherein cycling of the cleaning solution is improved.